ペロブスカイト型A Fe_<1-X>Co_xO_3(A=Sr, Ca)の強磁性 Ferromagnetic Properties of A Fe_<1-x>Co_xO_3(A=Sr, Ca)
AFe<SUB>1-x</SUB>Co<SUB>x</SUB>O<SUB>3-δ</SUB> (A=Sr, Ca) with minimized oxygen deficiency was prepared using high pressure technique. An oxider KCIO<SUB>4</SUB> was encapsulated with the sample powder. The Co-substitution makes Fe<SUB>3d</SUB> electrons of AFeO<SUB>3</SUB> more delocalized and induces metallic conduction and ferromagnetism. Cubic SrFe<SUB>1-x</SUB>Co<SUB>x</SUB>O<SUB>3</SUB> shows ferromagnetism above 300 K for 0.4≤x≤0.9. From the composition dependence of unit cell volume, a possibility of negative magnetovolume effect has been raised. In orthorhombic CaFe<SUB>1-x</SUB>Co<SUB>x</SUB>O<SUB>3</SUB> (0≤x≤0.5) Fe<SUB>3d</SUB> electrons seem to be more localized as judged from the magnetic hyperfine field measured by Mossbauer spectroscopy, and T<SUB>c</SUB> is lower and the magnetization is smaller in comparison with the Sr-analogue. These seem to indicate that the σ<SUP>*</SUP> band is narrow in the Ca-phase because the Fe-O-Fe band is bent to -150.
粉体および粉末冶金 43(8), 1001-1006, 1996-08-15
Japan Society of Powder and Powder Metallurgy